1. Field of the Invention
The present invention relates to a magnetic recording/playback apparatus for use in an electronic still camera of the type which employs a magnetic disk as a recording medium and, more particularly, to an automatic tracking apparatus for positioning a playback head in an optimum state with respect to a recording track.
2. Related Background Art
A conventional type of automatic tracking apparatus is arranged to move a playback head by means of a stepping motor and a moving mechanism. The playback head is moved to a desired track at a high speed and tracking control is started when the desired track is reached.
In another known arrangement, a playback head is moved by a small distance at a time while tracking control is being continuously performed until the desired track is reached.
Such a conventional type of automatic tracking apparatus, however, involves a number of problems. One problem is that the tracking speed is relatively slow. Another problem is that the position of the playback head may be offset from the desired track position. The reason for such offsetting is that a difference occurs between the one-track pitch of a head shifting mechanism and the actual one-track pitch of a magnetic sheet owing to various factors such as the thermal expansion or shrinkage of the magnetic disk or variations in individual track-to-track intervals resulting from the head shifting mechanism, although such variations are normally allowable ones which may occur in forming a recording track on the magnetic disk. Particularly when the playback head is moved over some tens of tracks, it may be possible that offsetting of 1/2 pitch track or thereabouts takes place.
If an offset occurs between the desired track position and the position to which the playback head has moved and if the desired track position is, for example, the center of the desired track (which is given by setting the distance to the track center determined by the standards concerned), the step position of the playback head is shifted to an intermediate position between successive tracks due to such offsetting, that is to say, a valley between successive playback RF envelope levels. The offsetting may lead to, for example, the problem that the subsequent tracking becomes unable to be reliably completed or tracks may be regarded as being unrecorded.